Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$222.41	3.304%	$229.7584	$229.76	$229.75	$229.80
Purchase #2	$85.31	11.323%	$94.9697	$94.97	$94.95	$95.00
Purchase #3	$196.62	11.148%	$218.5392	$218.54	$218.55	$218.50
Purchase #4	$148.81	6.609%	$158.6449	$158.64	$158.65	$158.60
Purchase #5	$92.34	11.670%	$103.1161	$103.12	$103.10	$103.10
Purchase #6	$190.63	4.826%	$199.8298	$199.83	$199.85	$199.80
Purchase #7	$241.31	7.160%	$258.5878	$258.59	$258.60	$258.60
7 purchase totals =	$1,177.43		$1,263.4459	$1,263.45	$1,263.45	$1,263.40